This invention relates to a timepiece, and more particularly to compensating for delays and advances in the hand movement of an analog electronic watch.
A conventional electronic watch 200 which is disclosed in Japanese Patent Publication No. 47512/1981, is illustrated in FIG. 2. Watch 200 is driven by a quartz oscillator. Intermittent rotational energy is accumulated through magnetic attraction between a driving magnet 71 and a driven magnet 73. Driving magnet 71 is coupled to a fourth pinion 15b. Driven magnet 73 is immersed in a viscous fluid 74; both of which are contained in a housing 76. Rotation of driven magnet 73 in viscous fluid 74 transforms the intermittent rotational movement of driving magnet 71 into a relatively constant, uninterrupted rotational force. Driven magnet 73 magnetically interlocks with a follower magnet 72. A relatively constant, smooth rotation of a hand spindle 15a, which is coupled to follower magnet 72, results. A cap 75 serves to seal viscous fluid 74 within receiver 76. The driving circuitry for watch 200 is based on a low power consuming type driving system such as disclosed in Japanese Patent Laid-Open Nos. 75520/1979, 77162/1979 and 87977/1980.
The degree of angular deviation between driving magnet 71 and driven magnet 73 varies based on the viscosity of viscous fluid 74. More particularly, as the temperature varies, the viscosity of viscous fluid 74 changes resulting in hand spindle 15a rotating either too quickly or too slowly. Discrepancies in the time displayed by watch 200 results. Alternatively, the increase in load associated with a calendar wheel train can cause the angular deviation between driving magnet 71 and driven magnet 73 to vary resulting in discrepancies in the time displayed by watch 200. The accuracy in time displayed by watch 200 is decreased.
Accordingly, it is desirable to provide a timepiece having hand sweep-driven movement in which accurate time is displayed. The accuracy in the displayed time should be maintained regardless of changes in ambient temperature or in load associated with a calendar mechanism.